(a) Field of the Invention
The present invention relates to a two-stage lock cylinder structure, and more particularly to a two-stage lock cylinder which uses a first joining member of a lock barrel to clamp with a second joining member of an actuating unit to enable achieving two-stage actuation as an unlocking operation for a locking device.
(b) Description of the Prior Art
Referring to FIG. 5, which shows a general lock cylinder comprising a lock casing (B), a lock barrel (C) and a key (D) (as shown in FIG. 6), wherein:
The lock casing (B) is provided with a holding hole (B1), and the lock casing (B) is further defined with a plurality of through holes (B2) that extend from the outer wall surface to the holding hole (B1), and a locking pin set (B3) is further fitted into each of the through holes (B3). Each of the locking pin sets (B3) comprises a locking piece (B31), a spring (B32), an upper locking pin (B33) and a lower locking pin (B34), length of each of the lower locking pins (B34) being different.
The lock barrel (C) is installed in the holding hole (B1) of the lock casing (B), and the lock barrel (C) is provided with a slot (C1) and a plurality of punched holes (C2) corresponding to the number of through holes (B2) of the lock casing (B). The punched holes (C2) extend from the outer wall surface to the slot (C1), and the punched holes (C2) of the lock barrel (C) intercommunicate with the through holes (B2) of the lock casing (B). The punched holes (C2) also enable the locking pin sets (B3) to penetrate therethrough.
Referring to FIG. 5, the lock barrel (C) is rotatably installed in the holding hole (B1) of the lock casing (B), and before the key (D) (as shown in FIG. 6) has been inserted into the slot (C1) of the lock barrel (C), the upper locking pins (B33) of the locking pin sets (B3) are positioned between the junction surface of the lock casing (B) and the lock barrel (C), thereby preventing the lock barrel (C) from rotating and causing the configuration to assume a locked state.
Referring to FIG. 6, after the key (D) has been inserted into the slot (C1) of the lock barrel (C), then notches (D1) of varying depth in the key (D) abut against the lower locking pins (B34) of the locking pin sets (B3) causing the lower locking pins (B34) to upwardly displace the upper locking pins (B33), thereby actuating the springs (B32) and causing the joining positions between the lower locking pins (B34) and the upper locking pins (B33) to assume a straight line corresponding to the junction surface between the lock casing (B) and the lock barrel (C), at which time, rotating the key (D) rotates the lock barrel (C), thereby unlocking the lock.
Shortcomings of the aforementioned prior art include: the locking pin sets (B3) of the lock casing (B) are easily damaged by external forces, and once a burglar extends a thin rod-shaped tool into the slot (C1) of the lock barrel (C), with the intention to effect the internal locking pin sets (B3) and move the lower locking pins (B34) and the upper locking pins (B33) of the locking pin sets (B3) to cause displacement thereof, and thereby cause the joining positions between the lower locking pins (B34) and the upper locking pins (B33) to assume a straight line corresponding to the junction surface between the lock casing (B) and the lock barrel (C), then the lock barrel (C) can be easily rotated to unlock the locking device; or means such as shaking, knocking, and so on, can be used to cause the upper locking pins (B33) to spring upwardly, and thereby cause the lock barrel (C) to rotate and unlock. Accordingly, using only the locking pin sets (B3) is insufficient to effectively secure the lock barrel (C), resulting in inferior burglar-proof ability of the locking device.